1. Field of the Invention
The invention relates to a color filter (CF), and more particularly to an arrangement of color elements for a color filter. Specifically, the arrangement of color elements is applicable to a color filter that fulfills requests for high resolution and high aperture ratio.
2. Description of the Related Art
As scientific and information technologies have advanced, a color filter (CF) has been popularly used in video products, such as color liquid crystal displays, charge coupled devices, and scanners, to obtain color information. With regard to a liquid crystal display (LCD) with light, thin, power-saving and full color features, including super-twisted-nematic (STN), thin-film-transistor (TFT) and metal-insulator-metal (MIN) types, a color filter with three primary colors including red (R), green (G) and blue (B) elements is needed to divide a pixel into R, G, and B subpixels. The three primary colors are blended with each other in proportion to create various colors, thus enabling bright, realistic, and vivid picture quality, enhancing functionality of the LCD.
The LCD mainly constitutes a TFT array substrate, a CF substrate, and a liquid crystal layer. In a conventional CF process, thin-film color layers including R, G, and B layers are successively coated on a glass substrate to serve as R, G, and B elements, after which the R, G, and B elements must be precisely aligned to pixel areas on the TFT array substrate. In view of manufacturing costs and quality requirements, dyeing, pigment dispersion, printing and electroplating are commonly used to form the R, G and B elements of the color filter. Particularly, pigment dispersion that provides the color filter with high precision and superior light- and heat-resistance has become a major CF process. In addition, a black matrix (BM) is disposed between the R, G, and B elements, shielding TFTs on the TFT array substrate from stray light, and preventing light leakage between pixels. Recently, the BM pattern has been omitted from the CF substrate to decrease process costs, and the light-blocking area is replaced by an overlapping portion of adjacent color elements on the CF substrate.
FIG. 1A is a top view of a strip-type RGB arrangement. FIG. 1B is a top view of a mosaic-type RGB arrangement. FIG. 1C is a top view of a delta-type RGB arrangement. The delta-type RGB arrangement provides simplified driving and optimum blend-mode effect, and is thus popularly applied to audio/video products.
FIG. 2A is a top view of a conventional strip RGB arrangement type with an overlapping portion between two adjacent color elements, and FIG. 2B is a cross-section along line 1xe2x80x941 of FIG. 2A illustrating an overlapping portion of two adjacent color elements. A conventional color filter 10 comprises a plurality of red elements 12R, green elements 12G and blue elements 12B in a strip RGB arrangement type. The red element 12R, green element 12G and blue element 12B have an identical width. Also, an overlapping portion 14 is formed by two adjacent color elements to serve as a light-blocking area. The overlapping portion 14, however, comprises a stack of two color coatings, and causes non-uniform distribution in pigment (or dye) thickness on a glass substrate. This protrusion damages uniformity of strength of electric fields and rotation of liquid crystal molecules within pixels, resulting in light leakage, decreased contrast ratio, poor color purity, and improperly mixed color. Moreover, with regard to a misalignment effect, the protrusion area of the overlapping portion 14 may increase, sacrificing aperture ratio, which is problematic in attaining a high-resolution LCD.
The present invention is an arrangement of color elements for a color filter. The arrangement of color elements is applicable to a color filter that fulfills requests for high resolution and high aperture ratio.
Accordingly, the present invention provides a color filter which comprises a plurality of color element groups. Each of the color element groups comprises a first color element, a second color element, a third color element and a fourth color element arranged in sequence. The first color element, the second color element, and the third color element comprising three colors. The second color element and the fourth color element are identical in color and width. An active width W1 of the first color element and an active width W2 of the second color element satisfy the formula: W1=Axc3x97W2, A=1.7xcx9c2.3. An active width W3 of the third color element and the active width W2 of the second color element satisfy the formula: W3=Bxc3x97W2, B=1.7xcx9c2.3.
Accordingly, the present invention also provides a color filter which comprises a plurality of color element groups. Each of the color element groups comprises a first color element, a second color element, a third color element, a fourth color element and a fifth color element arranged in sequence. The first color element, the second color element, and the third color element comprising three colors. The second color element and the fourth color element are identical in color and width. The third color element and the fifth color element are identical in color and width. An active width W1 of the first color element and an active width W2 of the second color element satisfy the formula: W1=Axc3x97W2, A=1.7xcx9c2.3. AN Active width W1 of the first color element and an active width W3 of the third color element satisfy the formula: W1=Bxc3x97W3, B=1.7xcx9c2.3.